Quantum Information Processing and Quantum Communications

Tomographic Quantum Cryptography: Equivalence of Quantum and Classical Key Distillation?

aula 102 - Martedì 4 maggio ore 14.00
  DAGMAR BRUSS, University of Hannover

>VITAE: Dagmar Bruss completed her PhD in Heidelberg in elementary particle physics. Spending two postdoc years in Oxford, she moved into the field of quantum information
in 1997. After one year at the ISI Torino (as European Research Fellow) she went to Hannover, where she is currently working in the Theoretical Quantum Optics group of Maciej Lewenstein. She completed her Habilitation in 2002. Her main scientific interests are the theory of entanglement, security issues in
quantum cryptography, and quantum optical implementations of quantum information processing.

Dagmar Bruss
  The security of a cryptographic key that is generated by communication through a noisy quantum channel relies on the ability to distill a shorter secure key sequence from a longer insecure one. For an important class of protocols, which exploit tomographically complete measurements on entangled pairs of any dimension, we show that the noise threshold for classical advantage distillation is identical with the threshold for quantum entanglement distillation. As a consequence, the two distillation procedures are equivalent: neither offers a security advantage over the other. This statement holds when only incoherent eavesdropping attacks are considered, but is modified for coherent ones.